Cylinder of a combustion engine with connected crankcase



(it, 11 1938.. A BERGER 2 1332,,84-2 CYLINDER O A COMBUSTION ENGINE WITH CONNECTED CRANKCASE Filed June 10, 1937 is x I 5 ii i i: I I 9 NI. Q

a z N Patented Oct. 11, 1938 PATENT OFFICE CYLINDER 0F COMBUSTION ENGINE WITH CONNECTED CRANKCASE Arthur Berger, Stuttgart-Oberturkheim, Germany, assignor to Daimler-Benz Aktiengesellschaft, Stuttgart-Unterturkheim, Germany Application June 10,

1937, Serial No. 147,410

In Germany May 16, 1937 3 Claims.

This invention relates to the cylinder of a combustion engine connectedwith the crank case, and more particularly is directed to means for preventing heat flow between such cylinder and crank case.

An object of my invention is the provision of an improved construction permitting continuous operation of an internal combustion engine at higher temperatures than heretofore possible.

Another object of my invention is the provision of an improved construction for preventing the flow of heat from an engine cylinder to the crank case of the engine.

A further object of my invention is the provision of an improved cylinder and crank case construction for an internal combustion engine, whereby a cooling fluid having a relatively high boiling point may be successfully utilized.

A more specific object of my invention is the provision of an improved construction wherein a cooling agent having a relatively high boiling point may be continuously used to cool cylinders of an internal combustion engine while at the same time the engine crank case and the lubricant therein is prevented from becoming too hot.

Further objects and advantages of this invention will be apparent from consideration of the specification as illustrated by the accompanying drawing of possible embodiments of the invention in which drawing:

Fig. 1 is a longitudinal cross-sectional View through a cylinder and crank case of an internal combustion engine illustrating a preferred embodiment of my invention; and

Fig. 2 is a cross-sectional view similar to Fig. 1 illustrating a modified form of my improved construction.

The improved combination of parts forming my invention is readily discernible in Figfl showing a preferred embodiment in which a is the crank case of an internal combustion engine and b the cylinder block connected therewith. The cylinder block if formed with the usual combustion space into which a liner 0 having at one end a flange Cl is preferably inserted; Between the flange d and the crank case a is interposed a thin layer of insualting material 1 which may consist of any suitable heat insulating materials known to the art. Connection between the liner c and the cylinder b is preferably made by means of external threads 9 cut on the lower end of the liner engaging suitable threads in the cylinder.

The crank case a and the cylinder 27 are preferably interconnected by means of bolts or studs cooperating with a nut or nuts h. In order that heat from the cylinder may not be transmitted to the crank case through the connecting means, a washer or disc of suitable heat insulating material i may be placed beneath the nut h.

The foregoing construction has the advantage that the engine cylinder may be cooled by an agent having a high boiling point, for example, above C. without the heat being transmitted to the crank case. As such a cooling agent, ethylene-glycol may be used which has a working temperature of C. to- C., although obviously this invention contemplates the use of any suitable fluid which can be safely used and whose boiling point liesabove 100 C.

It is well knownto those skilled in this art that high operating temperatures are desirable to im prove the efliciency of an internal combustion engine. When such high operating temperatures have heretofore been used, the resulting heat has been transmitted to the crank case, producing a mixture of hot and cold lubricating oil. It will be clear that in the crank case the oil which is found on the cooler walls will form a cool layer of oil, a so-called boundary layer which will not mix with the core of hot oil in the center. Thus, cooling of this hot oil is prevented by this layer of cool oil and the core of oil soon becomes so hot as to ruin it for lubricating purposes. For best operation, the temperature of the oil in the crank case should not exceed 100 C. By, however, interposing a layer of insulating material between the cylinder and the crank case, it is possible to utilize the advantages of a cooling fluid having a high boiling point without, at the same time, heating the oil above its optimum temperature.

The modified structure shown in Fig. 2 is identical in all respects with that shown in Fig. 1 except that no flange is formed on the lower part of the cylinder liner. A pad of insulating material e is directly interposed between the main cylinder portion 2) and the case a. The modified structure shown in Fig. 2 will give substantially the same results as that shown in Fig. 1. The thickness of the insulating sheath e is preferably slightly greater than that of the insulating material of f of Fig. 1 for the reason that in Fig. 1 the flange d on the cylinder liner also acts as an aid toprevent transmission of the undesirable heat.

The insulating sheath e may be formed of Bakelite, asbestos, or other suitable heat insulating material.

The invention is not intended to be limited to the two forms shown, which are to be understood as illustrative only and not as limiting, as various changes in construction and arrangement may be made, all coming within the scope of the claims which follow.

I claim:

1. In an internal combustion engine comprising, in combination, a cylinder, means within said cylinder defining a combustion space, passages surrounding said means adapted to receive a cooling agent, a crank case, means for attaching said crank case to said cylinder, insulating means for preventing transmission of heat from said cylinder to said crank case through said attaching means, and further heat insulating means interposed between said cylinder and said crank case, of suflicient thickness whereby a cooling fluid having a boiling point above 100 C. may be used for cooling said cylinder.

2. In an internal combustion engine having a cylinder provided with a combustion space surrounded by an appropriate cooling passage, and a crank case interconnected with said cylinder adapted to contain lubricating oil for said engine, the combination of heat insulating means entirely separating said cylinder and said crank case of sufiicient thickness for preventing the transmission of the heat of combustion to said crank case, whereby a cooling fluid having a boiling point of above 100 C. may be used for cooling said cylinder without heating said crank case and the oil therein above the optimum lubricating temperature of said oil.

3. In an internal combustion engine compris ing, in combination, a cylinder provided with a combustion space, means adapted to guide a cooling agent about the portion of said cylinder enclosing said combustion space, a crank case adapted to contain lubricating oil for said engine, means for attaching said crank case to said cylinder, and heat insulating means entirely sepa rating said cylinder and said crank case of sufiicient thickness for preventing the transmission of the heat of combustion to said crank case, whereby, when using a cooling agent capable of operating at a temperature above 100 0., said crank case and the oil therein will not be heated above the optimum lubricating temperature of said oil.

ARTHUR BERGER. 

